1. Field of the Invention
The present invention relates to a method and an apparatus for controlling a temperature of an injection preform for use in a stretch blow molding.
2. Description of Related Art
Conventionally, a far infrared radiation heater has been used for heating an intermediate product of a cylindrical bottle so-called a preform before the execution of the biaxial-orientation stretching blow molding. The preform used in the stretch blow molding is heated by radiation heat of the far infrared radiation heater, and it is necessary to rotate the preform and to heat it for a relatively long time in order to equally heat the surface of the preform.
However, since such a heating method using a far infrared radiation heater is normally arranged to fix a distance to the preform, the temperature dispersion in a longitudinal direction of the preform becomes unstable and therefore the thickness of the product tends to be fluctuated. Further, this conventional heating method requires a heating process equipment which has a relatively long longitudinal dimension. This increases the size of the equipment of such a bottle producing system and the consumption of electric energy for production.